This invention relates to a fastening device and more particularly to a fastener for joining layers of roofing material.
The present invention provides a fastener for joining a layer of insulation to a light weight deck or for joining two layers of insulation.
Heretofore, the joining of these materials has been accomplished through the utilization of a layer of hot asphalt applied between the two materials or by pre-drilling the deck and utilizing a toggle bolt as a fastener.
Besides being a costly and time consuming process, the use of toggle bolts often resulted in thermal bridging through the deck.
Fasteners such as that shown in Lancaster's British Pat. No. 11,242 utilize material engaging barbs, but fail to provide sidewall openings having the proper configuration necessary to allow the barb to exit in the desired direction and curl upon exiting.
It is an object of the present invention to provide a fastener that will securely join two pieces of light weight material such as roofing materials and one that will consistently perform in a reliable manner during installation i.e. will consistantly introduce a curling barb into the material.